The invention relates to a device for providing circulation in pump stations which are parts of a municipal sewage system.
As disclosed in U.S. Pat. No. 4,462,766, issued July 31, 1984, sludge banks occur in pump stations and other tanks in a sewage system due to poor circulation. Sludge banks can cause a number of problems including bad odors, risk of explosions, corrosion problems, etc.
According to the foregoing Patent, the problems have been solved by arranging a valve in the pump outlet, which is opened temporarily thus obtaining a circulation and flushing in the pump station. The sludge banks are dissolved and the fluid is homogenized.
The adjustment of the valve has been electrically controlled by means of a linear motor which acts upon a slide in the valve. A disadvantage with this solution, in addition to a relatively high cost, is that it easily becomes clogged as the pumped medium normally contains large amounts of solid bodies such as stones, rags and other objects. If a stone is stuck in the valve slide, the electric motor may break down.
Another disadvantage is that the motor of the valve is electrically driven which means specific installation problems where explosive gas may occur.